Six people have been sickened—two fatally—in a four-state listeriosis outbreak that began last September and has been traced to soft raw milk cheese made by Vulto Creamery of Walton, N.Y., which has issued a recall, federal officials said today.

The outbreak strain of Listeria monocytogenes is known to cause serious, life-threatening disease.

Deaths in Connecticut, Vermont

Listeria specimens were taken from two of the patients in September, one in October, and the other three in January, the Centers for Disease Control and Prevention (CDC) said in its first statement on the outbreak today.

Half of the patients are from New York, while Connecticut, Florida, and Vermont have each reported one case. All case-patients required hospitalization. The patients in Connecticut and Vermont died.

One of the patients is a newborn, the CDC said, while the oldest is 89 years old. The median age is 55, and five of the patients are female.

Whole-genome sequencing performed on the outbreak isolates showed they are closely related. "This close genetic relationship provides additional evidence that people in this outbreak became ill from a common source," the CDC said.

The person from Florida reported traveling to New York state and eating soft cheese there before becoming ill. The CDC said that Vulto Creamery cheese was for sale at stores where at least five of the outbreak patients bought cheese before falling ill.

In its investigation of the death of the person from Connecticut, the Connecticut Department of Public Health collected leftover cheeses from the patient's home. The agency identified the outbreak strain of Listeria in leftover cheese that the family identified as Ouleout cheese from Vulto Creamery.

In addition, the New York Division of Milk Control and Dairy Services collected three intact wheels of Vulto Creamery Ouleout cheese during a joint inspection with the Food and Drug Administration (FDA) and confirmed the outbreak strain of Listeria on the samples.

Vulto announces cheese recall

"The agencies have been investigating this outbreak since January 31, 2017," the FDA said in a statement today. "After gathering evidence about various cheeses eaten by the people who became ill, soft cheese from Vulto Creamery was identified as the likely source of the outbreak."

In response to the findings, Vulto Creamery began contacting customers on Mar 3 and on Mar 7 recalled all lots of Ouleout, Miranda, Heinennellie, and Willowemoc soft wash-rind raw milk cheeses, the FDA said. The cheese was distributed nationwide, with most of it sold at stores in the Northeast and Mid-Atlantic states; California; Chicago; Portland, Ore.; and Washington, D.C.

The FDA and CDC urge people not to eat any of the recalled products and to check their homes for them, and retailers and restaurateurs should not sell or serve them. Vulto Creamery says that consumers who have bought any of the recalled products should return them to the store for a full refund.

Raw milk cheese is made with milk that is not pasteurized, a process introduced in the late 1890s in the United States to destroy dangerous pathogens such as Listeria.

The CDC said the outbreak investigation is ongoing and it will provide updates as new information becomes available.